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Masahiko Shibahara - One of the best experts on this subject based on the ideXlab platform.
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Local Pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer scale slit pore obtained by the perturbative method
Journal of Chemical Physics, 2015Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal Local thermodynamic states: Local Pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the Local thermodynamic quantities from a molecular point of view. An instantaneous expression of the Local Pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the Local Pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative m...
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Local Pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer scale slit pore obtained by the perturbative method
Journal of Chemical Physics, 2015Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal Local thermodynamic states: Local Pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the Local thermodynamic quantities from a molecular point of view. An instantaneous expression of the Local Pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the Local Pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative method. The results revealed that the Local Pressure components tangential to the solid surface in the vicinity of the 1st fluid layer from the solid surface are different in a two dimensional plane, and the difference became pronounced in the vicinity of the corner of the slit, for cases where the fluid-solid interaction intensities are relatively strong. The results for the Local interfacial tensions of the fluid inside the slit suggested that the Local interfacial tensions in the vicinity of the 2nd and 3rd layers of the solid atoms from the entrance of the slit act as a trigger for the transition between the two states under the influence of a varying fluid-solid interaction.
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Local Pressure components and interfacial tension at a liquid solid interface obtained by the perturbative method in the lennard jones system
Journal of Chemical Physics, 2014Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the Pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the Pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the Local Pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the nu...
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Local Pressure components and interfacial tension at a liquid-solid interface obtained by the perturbative method in the Lennard-Jones system.
The Journal of chemical physics, 2014Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the Pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the Pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the Local Pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated Local Pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each Local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential Pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the Local Pressure components and interfacial tension at a liquid-solid interface.
K. Fujiwara - One of the best experts on this subject based on the ideXlab platform.
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Local Pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer scale slit pore obtained by the perturbative method
Journal of Chemical Physics, 2015Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal Local thermodynamic states: Local Pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the Local thermodynamic quantities from a molecular point of view. An instantaneous expression of the Local Pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the Local Pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative m...
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Local Pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer scale slit pore obtained by the perturbative method
Journal of Chemical Physics, 2015Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal Local thermodynamic states: Local Pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the Local thermodynamic quantities from a molecular point of view. An instantaneous expression of the Local Pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the Local Pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative method. The results revealed that the Local Pressure components tangential to the solid surface in the vicinity of the 1st fluid layer from the solid surface are different in a two dimensional plane, and the difference became pronounced in the vicinity of the corner of the slit, for cases where the fluid-solid interaction intensities are relatively strong. The results for the Local interfacial tensions of the fluid inside the slit suggested that the Local interfacial tensions in the vicinity of the 2nd and 3rd layers of the solid atoms from the entrance of the slit act as a trigger for the transition between the two states under the influence of a varying fluid-solid interaction.
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Local Pressure components and interfacial tension at a liquid solid interface obtained by the perturbative method in the lennard jones system
Journal of Chemical Physics, 2014Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the Pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the Pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the Local Pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the nu...
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Local Pressure components and interfacial tension at a liquid-solid interface obtained by the perturbative method in the Lennard-Jones system.
The Journal of chemical physics, 2014Co-Authors: K. Fujiwara, Masahiko ShibaharaAbstract:A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the Pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the Pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the Local Pressure components and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated Local Pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each Local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential Pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the Local Pressure components and interfacial tension at a liquid-solid interface.
Yuichiro Morishita - One of the best experts on this subject based on the ideXlab platform.
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Morphologic Evaluation of Lumbosacral Nerve Roots in the Vertebral Foramen: Measurement of Local Pressure of the Intervertebral Foramen.
Clinical spine surgery, 2017Co-Authors: Yuichiro Morishita, Takeshi Maeda, Takayoshi Ueta, Muneaki Masuda, Keiichiro ShibaAbstract:Study design The prospective cohort study. Objective of the study The objective was to evaluate the relationships between Local Pressure changes of the intervertebral foramen during lumbar spine extension and lumbar foraminal morphology. Summary of background data The physiological states of lumbosacral nerve roots in the vertebral foramen remain controversial. Methods We evaluated 56 lumbosacral vertebral foramens in 21 patients with L4-degenerative spondylolisthesis. All patients underwent L4-5 posterolateral fusion (PLF). The Local Pressure of the intervertebral foramen was measured intraoperatively, and measurement was performed before and after L4-5 PLF. We defined the changes in the ratio of Local Pressure between lumbar flexion to extension as percent Pressure. The sagittal angular motion, distance between the inferior cortex of the cranial pedicle and superior cortex of the caudal pedicle, posterosuperior margin of the superior vertebral body and superior articular facet, posteroinferior edge of the superior vertebral body and inferior articular facet, and the intervertebral disc height were measured using preoperative functional plain radiographs and CT images. Results The average Local Pressure of the intervertebral foramen significantly increased during lumbar extension. However, the L4-5 vertebral foraminal Pressure after PLF were nearly identical. There was no significant correlation between percent Pressure and lumbar range of motion. Furthermore, there were no significant correlations between percent Pressure and each morphologic parameter of the lumbar foramen. Conclusions There were no significant relationships between the lumbar foraminal morphology and intervertebral foraminal Pressure changes during lumbar extension, and L4-5 vertebral foraminal Pressure was not affected by the lumbar posture after L4-5 posterior fusion. On the basis of the results, the external dynamic stresses on the nerve roots in the vertebral foramen might be improved by lumbar posterior fusion using instrumentation without direct decompression of the vertebral foramen.
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Pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen: measurement of Local Pressure of intervertebral foramen.
Spine, 2014Co-Authors: Yuichiro Morishita, Masatoshi Naito, Takeshi Maeda, Takayoshi Ueta, Keiichiro ShibaAbstract:STUDY DESIGN Measurement of Local Pressure of the intervertebral foramina. OBJECTIVE To evaluate the pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA The physiological states of lumbosacral nerve roots in the vertebral foramen remain controversial. METHODS From 2000 to 2012, 11 of 710 patients with L4 degenerative spondylolisthesis failed to develop postoperative radiculopathy because of intraoperative pedicle screw malposition (L5: 10, L4: 1). We prospectively evaluated the Local Pressure at the L4-L5 and L5-LS vertebral foramina in 18 patients with L4 degenerative spondylolisthesis. All patients underwent L4-L5 posterolateral fusion (PLF) with L3-L4-L5 laminotomy. Intraoperatively, Local Pressure of the intervertebral foramen was measured using a catheter Pressure transducer while changing the lumbar spine posture, and the measurement was performed before and after L4-L5 PLF. RESULTS The Local Pressures at the L4-L5 vertebral foramen were 29.74 ± 16.26 and 51.57 ± 23.18 mm Hg (before fixation), and 39.13 ± 17.69 and 41.71 ± 17.94 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The Local Pressure before fixation increased significantly during lumbar spine extension (P < 0.001), although the value after fixation was almost identical. The Local Pressures at the L5-LS vertebral foramen were 26.91 ± 18.16 and 54.36 ± 26.67 mm Hg (before fixation), and 24.82 ± 17.1 and 58.46 ± 32.78 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The Local Pressure before and after fixation increased significantly during lumbar spine extension (P < 0.001), and the values after fixation were higher than those before fixation. CONCLUSION The Local Pressure at the L4-L5 vertebral foramen did not change during lumbar extension after L4-L5 PLF, whereas the Local Pressure at the L5-LS vertebral foramen was significantly increased during lumbar extension after L4-L5 PLF. Our results suggested that the nerve roots caudal to the fixed segments may be exposed to higher external dynamic stresses after lumbar instrumentation surgery. LEVEL OF EVIDENCE 4.
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Neurogenic intermittent claudication in lumbar spinal canal stenosis: the clinical relationship between the Local Pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis
Journal of spinal disorders & techniques, 2009Co-Authors: Yuichiro Morishita, Shinichi Hida, Masatoshi Naito, Jun Arimizu, Yoshihiro TakamoriAbstract:STUDY DESIGN The clinical relationship between the Local Pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis were evaluated. OBJECTIVE To investigate the pathogenesis of neurogenic intermittent claudication in lumbar spinal canal stenosis. SUMMARY OF BACKGROUND DATA The genesis of neurogenic intermittent claudication is generally considered to result from nerve root ischemia; however, the exact pathogenesis of neurogenic intermittent claudication remains uncertain. METHODS From a total of 20 lumbar spinal canal stenosis patients, 29 L5/S1 vertebral foramens were studied. All patients showed neurogenic intermittent claudication, and also showed neurologic abnormalities in L5 area. Intraoperatively, the Local Pressure of the intervertebral foramen was continuously measured using a micro-tip catheter transducer whereas the lumbar spine postures were changed under passive movement, and the relationships between the Local Pressure and the preoperative clinical findings in lumbar spinal canal stenosis were analyzed. RESULTS The Local Pressure of the intervertebral foramen significantly increased during lumbar spine extension (P
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Measurement of the Local Pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots in the vertebral foramen.
Spine, 2006Co-Authors: Yuichiro Morishita, Shinichi Hida, Masatoshi Naito, Jun Arimizu, Ushio Matsushima, Atsuhiko NakamuraAbstract:STUDY DESIGN The intraoperative findings of the Local Pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots were evaluated. OBJECTIVE To investigate the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA As far as we know, few reports have so far described the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. METHODS The Local Pressure of the intervertebral foramen was continuously measured while the lumbar spine posture was changed in 66 vertebral foramens. In addition, 20 L5 nerve roots were electrophysiologically evaluated using the compound muscle action potentials (CMAPs) from tibialis anterior (TA) muscle after L5 nerve root stimulation. RESULTS The Local Pressure of the intervertebral foramen was significantly increased during lumbar spine extension (P < 0.001); moreover, the latency and amplitude of the CMAPs both significantly deteriorated in line with the increasing Local Pressure. CONCLUSIONS Our findings suggested that a double compression of the nerve root exists in lumbar spinal stenosis with lumbar spine extension, which includes the spinal canal and the vertebral foramen.
Masatoshi Naito - One of the best experts on this subject based on the ideXlab platform.
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Pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen: measurement of Local Pressure of intervertebral foramen.
Spine, 2014Co-Authors: Yuichiro Morishita, Masatoshi Naito, Takeshi Maeda, Takayoshi Ueta, Keiichiro ShibaAbstract:STUDY DESIGN Measurement of Local Pressure of the intervertebral foramina. OBJECTIVE To evaluate the pathophysiological effects of lumbar instrumentation surgery on lumbosacral nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA The physiological states of lumbosacral nerve roots in the vertebral foramen remain controversial. METHODS From 2000 to 2012, 11 of 710 patients with L4 degenerative spondylolisthesis failed to develop postoperative radiculopathy because of intraoperative pedicle screw malposition (L5: 10, L4: 1). We prospectively evaluated the Local Pressure at the L4-L5 and L5-LS vertebral foramina in 18 patients with L4 degenerative spondylolisthesis. All patients underwent L4-L5 posterolateral fusion (PLF) with L3-L4-L5 laminotomy. Intraoperatively, Local Pressure of the intervertebral foramen was measured using a catheter Pressure transducer while changing the lumbar spine posture, and the measurement was performed before and after L4-L5 PLF. RESULTS The Local Pressures at the L4-L5 vertebral foramen were 29.74 ± 16.26 and 51.57 ± 23.18 mm Hg (before fixation), and 39.13 ± 17.69 and 41.71 ± 17.94 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The Local Pressure before fixation increased significantly during lumbar spine extension (P < 0.001), although the value after fixation was almost identical. The Local Pressures at the L5-LS vertebral foramen were 26.91 ± 18.16 and 54.36 ± 26.67 mm Hg (before fixation), and 24.82 ± 17.1 and 58.46 ± 32.78 mm Hg (after fixation) in the lumbar spine neutral and extension postures, respectively. The Local Pressure before and after fixation increased significantly during lumbar spine extension (P < 0.001), and the values after fixation were higher than those before fixation. CONCLUSION The Local Pressure at the L4-L5 vertebral foramen did not change during lumbar extension after L4-L5 PLF, whereas the Local Pressure at the L5-LS vertebral foramen was significantly increased during lumbar extension after L4-L5 PLF. Our results suggested that the nerve roots caudal to the fixed segments may be exposed to higher external dynamic stresses after lumbar instrumentation surgery. LEVEL OF EVIDENCE 4.
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Neurogenic intermittent claudication in lumbar spinal canal stenosis: the clinical relationship between the Local Pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis
Journal of spinal disorders & techniques, 2009Co-Authors: Yuichiro Morishita, Shinichi Hida, Masatoshi Naito, Jun Arimizu, Yoshihiro TakamoriAbstract:STUDY DESIGN The clinical relationship between the Local Pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis were evaluated. OBJECTIVE To investigate the pathogenesis of neurogenic intermittent claudication in lumbar spinal canal stenosis. SUMMARY OF BACKGROUND DATA The genesis of neurogenic intermittent claudication is generally considered to result from nerve root ischemia; however, the exact pathogenesis of neurogenic intermittent claudication remains uncertain. METHODS From a total of 20 lumbar spinal canal stenosis patients, 29 L5/S1 vertebral foramens were studied. All patients showed neurogenic intermittent claudication, and also showed neurologic abnormalities in L5 area. Intraoperatively, the Local Pressure of the intervertebral foramen was continuously measured using a micro-tip catheter transducer whereas the lumbar spine postures were changed under passive movement, and the relationships between the Local Pressure and the preoperative clinical findings in lumbar spinal canal stenosis were analyzed. RESULTS The Local Pressure of the intervertebral foramen significantly increased during lumbar spine extension (P
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Measurement of the Local Pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots in the vertebral foramen.
Spine, 2006Co-Authors: Yuichiro Morishita, Shinichi Hida, Masatoshi Naito, Jun Arimizu, Ushio Matsushima, Atsuhiko NakamuraAbstract:STUDY DESIGN The intraoperative findings of the Local Pressure of the intervertebral foramen and the electrophysiologic values of the spinal nerve roots were evaluated. OBJECTIVE To investigate the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. SUMMARY OF BACKGROUND DATA As far as we know, few reports have so far described the neurophysiologic changes of the spinal nerve roots in the vertebral foramen. METHODS The Local Pressure of the intervertebral foramen was continuously measured while the lumbar spine posture was changed in 66 vertebral foramens. In addition, 20 L5 nerve roots were electrophysiologically evaluated using the compound muscle action potentials (CMAPs) from tibialis anterior (TA) muscle after L5 nerve root stimulation. RESULTS The Local Pressure of the intervertebral foramen was significantly increased during lumbar spine extension (P < 0.001); moreover, the latency and amplitude of the CMAPs both significantly deteriorated in line with the increasing Local Pressure. CONCLUSIONS Our findings suggested that a double compression of the nerve root exists in lumbar spinal stenosis with lumbar spine extension, which includes the spinal canal and the vertebral foramen.
Yoshihiro Takamori - One of the best experts on this subject based on the ideXlab platform.
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Neurogenic intermittent claudication in lumbar spinal canal stenosis: the clinical relationship between the Local Pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis
Journal of spinal disorders & techniques, 2009Co-Authors: Yuichiro Morishita, Shinichi Hida, Masatoshi Naito, Jun Arimizu, Yoshihiro TakamoriAbstract:STUDY DESIGN The clinical relationship between the Local Pressure of the intervertebral foramen and the clinical findings in lumbar spinal canal stenosis were evaluated. OBJECTIVE To investigate the pathogenesis of neurogenic intermittent claudication in lumbar spinal canal stenosis. SUMMARY OF BACKGROUND DATA The genesis of neurogenic intermittent claudication is generally considered to result from nerve root ischemia; however, the exact pathogenesis of neurogenic intermittent claudication remains uncertain. METHODS From a total of 20 lumbar spinal canal stenosis patients, 29 L5/S1 vertebral foramens were studied. All patients showed neurogenic intermittent claudication, and also showed neurologic abnormalities in L5 area. Intraoperatively, the Local Pressure of the intervertebral foramen was continuously measured using a micro-tip catheter transducer whereas the lumbar spine postures were changed under passive movement, and the relationships between the Local Pressure and the preoperative clinical findings in lumbar spinal canal stenosis were analyzed. RESULTS The Local Pressure of the intervertebral foramen significantly increased during lumbar spine extension (P
